v3.22.0.1
Stockholders' Equity (Tables)
 12 Months Ended
Dec. 31, 2021
Equity [Abstract]  
Summary of Stock Options and SAR Activity
A summary of stock option and SAR activity for the year ended December 31, 2021 is as follows (in millions, except share amounts which are reflected in thousands, per share amounts, and years):
SARs Outstanding Number of SARsOptions Outstanding Number of SharesWeighted-Average Exercise Price Per ShareWeighted-Average Remaining Contractual Life (in years)Aggregate Intrinsic Value
As of December 31, 2020229 28,734 $12.87 4.97$1,104 
Granted and assumed in connection with acquisitions— 5,457 $5.13 
Exercised(65)(9,380)$10.81 
Canceled and forfeited(7)(558)$17.14 
As of December 31, 2021157 24,253 $11.84 4.35$735 
Vested and expected to vest as of December 31, 2021134 17,411 $8.10 3.55$593 
Exercisable as of December 31, 2021134 17,411 $8.10 3.55$593 
Schedule of Restricted Stock Units Activity
The following table summarizes the activity related to our RSUs for the year ended December 31, 2021 (in thousands, except per share amounts):
Number of SharesWeighted-Average
 Grant-Date Fair
 Value per Share
Unvested and outstanding as of December 31, 202083,736 $34.17 
Granted50,308 $49.78 
Vested(39,005)$37.98 
Canceled and forfeited(23,578)$37.85 
Unvested and outstanding as of December 31, 202171,461 $41.91 
Schedule of Restricted Common Stock
The following table summarizes the activity related to our restricted common stock for the year ended December 31, 2021 (in thousands, except per share amounts):
Number of SharesWeighted-Average
 Grant-Date Fair
 Value per Share
Unvested restricted common stock as of December 31, 202028 $34.86 
Granted4,641 $43.50 
Vested(516)$43.50 
Canceled and forfeited— $— 
Unvested restricted common stock as of December 31, 20214,153 $43.44 
Schedule of Stock-Based Compensation Expense by Function The following table summarizes total stock-based compensation expense by function for the years ended December 31, 2019, 2020 and 2021 (in millions):
Year Ended December 31,
201920202021
Operations and support$454 $72 $139 
Sales and marketing243 48 83 
Research and development2,958 477 614 
General and administrative941 230 332 
Total$4,596 $827 $1,168 
Schedule of Weighted Average Assumptions The fair value of stock options and SARs granted was determined using the Black-Scholes option-pricing model with the following weighted-average assumptions:
Year Ended December 31,
201920202021
Expected term (in years)6.04.05.1
Risk-free interest rate2.2 %0.3 %0.9 %
Expected volatility33.9 %42.5 %40.3 %
Expected dividend yield— %— %— %
The fair value of performance awards with market-based targets granted was determined using a Monte Carlo model with the following weighted-average assumptions:
Year Ended December 31,
201920202021
Risk-free interest rate2.7 %— %— %
Expected volatility39.0 %— %— %
Expected dividend yield— %— %— %